Astronomers report the first atmosphere on a rocky planet in a habitable zone

LHS 1140b, 49 light years away, shows signs of an atmosphere — a first for a rocky habitable-zone planet, though composition stays unconfirmed.

Researchers have reported detecting an atmosphere around LHS 1140b, a rocky exoplanet 49 light years away. The study describes it as the first observationally confirmed atmosphere on a rocky planet in a star's habitable zone outside our solar system. Dr Collin Cherubim, formerly of Harvard University, is the first author, and the findings appear in Science.

The planet has 5.6 times Earth's mass and a radius 70% larger. It is tidally locked, may hold far more water than Earth, and orbits a small red dwarf in the constellation Cetus, discovered in 2017. The red dwarf is dimmer than the Sun but emits a larger share of its energy as ionising radiation. Using an infrared spectrograph on the Magellan Clay telescope in Chile, the team watched the planet cross its star. Data from 2024 showed helium escaping into space — but that helium was absent in 2025 observations, prompting re-analysis. A companion planet, LHS 1140c, showed no atmosphere.

Knowing whether rocky worlds beyond our system can hold onto air sharpens the search for life and refines the methods we use to look. This is knowledge for the commons: no product ships, but the map of what is out there grows more precise.

Caveats run through the result. The signal concerns gas escaping the upper atmosphere, not the surface. One researcher, Dr Yamila Miguel, said she does not think the findings bear directly on detecting life. The atmosphere's composition and the planet's habitability remain unconfirmed.

Source: Guardian